Process of washing out sucrate of lime.



No. 664,906. Patented Jan. 19m.

' c. STEFFEN.

PROCESS OF WASHING OUT SUCBATE 0F LIME.

(Application-81nd Apr. 6, 1898.)

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UNTTED STATES PATENT OFFICE.

CARL STEFFEN, OF VIENNA, AUSTRIA-HUNGARY.

PROCESS OF WASHING OUT SUCRATE OF LIME.

SPECIFICATION formingpart of Letters Patent No. 664,906, dated January1, 1901.

Application filed April 6,1898. Serial No. 676,685. (No specimens.)

Q0 to whom, it may concern.-

Be it known that I, CARL STEFFEN, engineer, a subject of the Emperor ofAustria-Hungary, and a residentof No. 40 Hengasse, Vienna, in the Empireof Austria-Hungary, have invented a certain new and useful ImprovedProcess for \Vashing Out Sucrate of Lime, of which the following is afull, clear, and exact description.

This invention relates to a process of obtaining pure sucrate orsaccharate of lime as such is obtained according to known processes ofprecipitating sucrate of lime from impure aqueous liquors, syrups, ormolasses by a pcculiar new method of filtering or separating the sucrateof lime from the mother-liquor in filter-presses or similar apparatus,such filtering simultaneously effecting the washing of the sucrate oflime.

Figure l is an elevation of the apparatus for carrying out the process;Fig. 2, an end elevation of the filtering-press; Fig. 3, acrosssectionthrough one chamber of the press on a larger scale, showing theformation of the cakes within the press-chamber in accordance with thisprocess.

According to known processes for precipitating sucrate of lime suchprocesses are usually carried out in such a manner that in order not tocause any unnecessary loss of sugar or obtain too thin and too muchwaste lye sugar liquors are used which possess the highest possibleconcentration, but still allow of a good separation of the precipitatefrom the mother-liquor. The sucrate of lime precipitated from such lyesis then filtered in filter-presses from the mother-lye and the obtainedsugar-lime cakes are washed with water, clear lime-water, or a solutionof sucrate of lime. The wash-water is either reemployed for diluting anew liquor or passed off as waste lye. This method of washing out hasgreat drawbacks, is unreliable, and faulty, since a great quantity ofwashing liquid is necessary for properly washing the sucrate. Thesucrate cakes are, on the one hand, loosened at the periphery of. themud-frame or at less compact parts by the one-sided pressure of thewashing liquid and, on the other hand, fine fissures and pores areformed in the mud mass which effects an unequal penetration of the mudcakes with washing liquid, so that such cakes are irregularly washed,much wash-water is used, and consequently not sufiiciently pure sucrateobtained. If the filterpresses were put under too strong pressure, thewashing would be rendered difficult.

The object of this invent-ion is to overcome the disadvantages ordrawbacks.

According to my process the sucrate remaining behind in the filter pressis not washed by clear washing liquids, but by means of suchliquids inwhich sucrate of lime is suspended, which is adapted, on the one hand,to immediately fill up the fine interstices and pores formed during thewashing and, on the other hand, to exert during and at the completion ofthe washing an increased pressure on the sucrate mass within thefilterframes. This washing liquid containing the suspended precipitateof sucrate of lime enters during the washing process in the filterpressnot behind the cakes, but passes through the same mud -channel throughwhich the original lye was driven into the filter-press.

The operation is eifected in such a manner that the original lye inwhich the precipitated sucrate of lime is present is first passed orfeed to the filter-press through the mud channel or passage in the usualmanner until the filter-frames are partly filled with a suitablequantity, (about eighty per cent.) The feed of original lye is theninterruptedt'. 6., stopped by valves. Now the washing liquid containinginsoluble suspended precipitate of sucrate of lime is pressed into thefilterpress under sufficient pressure until the free spaces of thechambers of the press are filled up with the precipitate.

The following method may be adopted for producing the washing liquid forsuch sucrates of lime: The washing liquid is produced from the sugarsubstance, (syrup or molasses,) from which also the concentratedoriginal lyes are formed. For this purpose the syrup or molasses isdiluted with so much pure water that in one hundred parts only a smallquantity of saccharate or nonsaccharate substance is contained. Theproportions are one and one-half per cent. sugar and about seven-tenthsto one per cent. nonsaccharine substance. Sucrate of lime is thenprecipitated from this thin liquor in the usual manner by introducinglime and an insoluble sucrate is formed in the washing liquid. Since thequantity of non-saccharine substance in the washingliquid is very small,the same is of no moment for the washing process of the sucrate which ispresent in the filter-press from the concentrated original lye. Thevessels or receptacles A and A serve for precipitating the sucrate oflime from aqueous sugar liquors by means of lime in the known manner.For this purpose the vessel A is fed with molasses or impure sugarliquor from the vessel B, and the molasses is diluted with water orwashing liquid from the vessels 0 and C, respectively, to aconcentration of six to ten per cent. sugar, advantageous for theprecipitation. After this liquid has been produced in the vessel Alime-powder is fed to this vessel from the hopper D or thedisintegrating apparatus E connected therewith, and the precipitation ofsucrate of lime is thereby effected in the Vessel A in the known manner.In the vessel A the same molasses or impure sugar liquor fed from thevessel B is likewise didilnted with water from the vessel 0communicating with A to a considerably lower concentration than theliquid in the vessel A.

' 1 The dilution is preferably such that in one hundred parts liquid thecontents of nonsaccharine matter are below three per cent. or preferablyamount to only about one per cent. This diluted liquid in the vessel Ais likewise fed with lime from the hopper D and the disintegratingapparatus E, respectively, andin this manner a precipitation of sucrateof lime is effected in the vessel A.

After the liquids containing precipitated sucrate of lime have beenproduced in the vessels A A in the above-described manner the filtrationof same in a filter-press F is carried out as follows: By means of apump G, which is connected to the filter-press by a pipe, the valve 11of which is open, the contents of the vessel A are pressed or forcedinto the filter-press, which is filled up to about four-fifths of itscapacity with precipitated sucrate of lime. This partial filling of thepress can most conveniently be ascertained by the pressure indicated ona manometer of the pump G. It is recommended to work with the pump G upto a pressure of about three atmospheres, since in this case the pressis filled up to about four-fifths of its capacity. Now the valve H isclosed and by means of a pump G the diluted liquid is pressed or forcedfrom the vessel A into the filtenpress, the valve H being open. Thediluted precipitating liquid is pressed from the vessel A into thefilter-press F until the chambers of the same are completely filled withsucrate of lime. This takes place when the manometer of the pump Gindicates a pressure of aboutsix to eight atmospheres. At this momentthe process is finished. The material remaining behind in thefilter-press is a very pure sucrate of lime, which need not be subjectedto a further washing process.

Fig. 3 is a cross-section through a filterframe J, arranged between thefilter-plates K K. L indicates the opening or channel through which theconcentrated liquid is first the sucrate of limewhile the mother-lyeofthe diluted liquid from the vessel A contains less quantities ofnon-saccharine matter, and consequently can displace the lye of thesucrate from the more concentrated liquid taken from the vessel A, whichlye is richer in nonsaccharine matter and forms the layers M of thefilter-press chambers.

This process may not only be carried out in filter-presses, but also insuction apparatus, centrifugal machines, and similarapparatus.

Having now particularlydescribed and ascertained the nature of the saidinvention, I declare that what I claim, and wish to secure by LettersPatent, is-- The process of washing out sucrate of lime infilter-presses consisting in only partly filling the filter-press withthe substance to be washed and subsequently supplying the space, whichis not occupied by such substance, with less concentrated washing liquidconsisting of a mixture of water and insoluble precipitate of lime, forthe purpose of filling up the porous places formed in the impuresubstance during the washing process and of enabling a uniformpenetration of'the washing liquid and formation of solid cakes bysimultaneously subjecting the substance to be washed to a strongpressure, substan- V CARL STEFFEN.

Witnesses:

HENRY C. CARPENTER, CHAS. E. CARPENTER.

